Sure, some come in and help immediately, but most have to be guided through the transition to a higher level of play.

Substitute "rookie" for "freshman" and you'll get the same reaction from an NFL coach.

That's why Mike Tomlin isn't nearly as excited about having Dennis Dixon start the Pittsburgh Steelers' first four games at quarterback as a lot of fans are.

The fans saw Dixon play effectively in the second half of last Saturday's preseason opener against the Detroit Lions.

That came after veteran Byron Leftwich had a mediocre performance in the first half.

But it's all about context, and here's what Tomlin knows:

Leftwich, for whatever flaws he has, has won in the NFL. He's probably good enough to get the Steelers through the start of the season until Ben Roethlisberger returns from his NFL-inposed suspension.

Tomlin also knows that there's no game planning or specific defensive scheming in the preseason. Teams play everything pretty basic so they don't offer any previews of what's coming in the regular season.

Tomlin knows, too, that the second half of the first preseason game is populated by guys who will soon be packing and heading home.

No roster cuts have been made yet, and the free agent dreamers are still suiting up for games.

Tomlin would never say this, but it's a fact: The Lions are 2-30 over the past two regular seasons.

Their first string isn't good enough to beat anyone; how good are the guys who are backing up?

Dixon isn't a rookie, but he's started just one game in the NFL and the Steelers scaled back the offense so he could handle it.

As exciting as some of Dixon's runs may have been, they didn't impress offensive coordinator Bruce Arians, who saw what should have happened on some of those plays.

"We had wide open receivers," Arians said. "It's fine to run when there's nobody open, but when there are open receivers, get them the ball."

The ability to make those decisions comes with experience.

The Steelers could change their thinking if Leftwich doesn't show anything in the pre-season.